The present invention relates to a flow-through filter medium product and more particularly to a unique and novel unified filter medium, border frame therefore and method of assembling the novel filter medium to the border frame to assure a sturdy and stable unit filter arrangement for efficient treatment of a high velocity fluid stream.
It has been long known to utilize thermoplastic, melt blown materials for filtration purposes, attention being directed to U.S. Pat. No. 5,531,235, issued to C. B. Hassenboehler, jr. et al on Jul. 2, 1996, which utilizes such an arrangement in the manufacturing of cigarette filters. Attention is further directed to the heat bonding arrangements disclosed in U.S. Pat. No. 5,652,041, issued to G. K. Buerger et al on Jul. 29, 1997; U.S. Pat. No. 5,709,735, issued to D. G. Midkiff et al on Jan. 20, 1998; U.S. Pat. No. 6,159,318, issued to Kyung-Ju Choi on Dec. 12, 2000; and, to U.S. Pat. No. 6,254,653, issued to Kyung-Ju Choi et al on Jul. 3, 2001. In addition to the heat bondable filter medium set forth in each of these aforementioned patents, attention also is directed to the border frame supports units and manufacturing processes disclosed in certain of these aforementioned patents.
Recognizing the broad features of the prior art as taught by the prior art, the present invention provides an efficient, economical, and, straight forward structure for a unique filter medium with compressed edges which enhances both binding assembly and subsequent filtration efficiency. The present invention further provides a unique and compatible unified border frame member to cooperatively receive and support such novel filter medium of the present invention and which also enhances filter unit assembly sealing operations. In addition, the present invention provides a unique and novel unified assembly arrangement requiring a minimum of efficient and economical steps to sealingly join the novel filter medium and novel border frame member to produce an efficient, sturdy and stable filter unit, capable of ready installation for the filter treatment of high velocity fluid streams.
Various other features of the structural arrangement of the novel edge treated filter medium, novel support border frame therefore and the novel method, all as disclosed in a unified manner herein, will become obvious to one skilled in the art upon reading the disclosure set forth herein.
More particularly the present invention provides a unique fibrous filter medium which lends itself to ready assembly with the novel border frame arrangement also further described herein and to the unified novel assembly method also described hereinafter.
Specifically, the present invention provides a novel self-supporting pleated fluid filter medium including opposed upstream and downstream faces comprising at least one sheet of thermoplastic synthetic fibrous material which can be of low melt attenuated fibers with selected denier characteristics or a dri-laid blend of chopped fibers of selected size and diameter. The fibrous material should have at least a sufficient stiffness to provide for self-supporting pleats sufficient to maintain pleat form during an anticipated fluid filtering treatment velocity. Advantageously, the inventive sheet of thermoplastic fibrous material can be up to one hundred (100) percent (%) by weight of preselected thermoplastic fibers comprising dri-laid blended chopped fibers comprising zero point five (0.5) to forty (40) denier fibers, with fiber lengths of zero point three (0.3) to three (3) inches, or, if of melt blown material with fiber sizes in the range of approximately zero point three (0.3) to thirty-five (35) micrometers.
In addition, the present invention provides a novel border frame member comprised of at least one strip of material, the strip being conformably sized to engage opposed peripheral edge faces of thermoplastic fluid filter medium to be bonded thereto.
Further, the present invention also provides a novel method of assembling the selectively sized and configured pleated unit filter medium and the border frame which incorporates thermobondable coated materials comprising: heat softening selected edges of at least one thermobondable unit filter medium layer; compressing selected edges of the unit filter medium into substantially rigid border edges mounting the unit filter medium unto a compatibly sized and configured thermobondable border frame having selected filter medium support edges to receive and support the border edges of the unit filter medium in facing relationship therewith; and thermobonding the facing edges of the unit filter medium and the border frame in sealed relation.
It is to be understood that various changes can be made by one skilled in the art in one or more of the several features and parts of the novel filter medium and the novel flow-through border frame, as well as in one or more of the several steps of the inventive method described herein without departing from the scope or spirit of the present invention.